WO2011070985A1 - Appareil photoacoustique, et procédé de commande associé - Google Patents

Appareil photoacoustique, et procédé de commande associé Download PDF

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Publication number
WO2011070985A1
WO2011070985A1 PCT/JP2010/071748 JP2010071748W WO2011070985A1 WO 2011070985 A1 WO2011070985 A1 WO 2011070985A1 JP 2010071748 W JP2010071748 W JP 2010071748W WO 2011070985 A1 WO2011070985 A1 WO 2011070985A1
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Prior art keywords
light
analyte
optical
optical absorber
light source
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PCT/JP2010/071748
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English (en)
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WO2011070985A4 (fr
Inventor
Akira Sato
Yoshiaki Sudo
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Canon Kabushiki Kaisha
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Application filed by Canon Kabushiki Kaisha filed Critical Canon Kabushiki Kaisha
Priority to US13/514,955 priority Critical patent/US9084560B2/en
Publication of WO2011070985A1 publication Critical patent/WO2011070985A1/fr
Publication of WO2011070985A4 publication Critical patent/WO2011070985A4/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0093—Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy
    • A61B5/0095—Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy by applying light and detecting acoustic waves, i.e. photoacoustic measurements

Definitions

  • the present invention relates to a photoacoustic apparatus that receives a photoacoustic wave generated when an analyte is irradiated with light.
  • Patent Literature 1 irradiates a living body with pulsed light generated from a light source and detects an acoustic wave generated from a living tissue absorbing the energy of the pulsed light propagating through and diffused in the living body
  • the technique uses a difference in absorptance of light energy between a detection portion such as a tumor and the other tissues, and receives by receiving elements an elastic wave that is generated when the detection portion absorbs the light energy and instantly expands.
  • the information can be used in measurement for an optical characteristic distribution in a living body, and more particularly, quantitative measurement for a specific substance in the analyte, for example, glucose or hemoglobin contained in the blood.
  • the information can be used for specifying the position of a malignant tumor accompanying with the growth of new blood vessels.
  • a light-energy absorption-density distribution can be obtained.
  • ⁇ is a Gruneisen coefficient (heat-acoustic conversion efficiency)
  • ⁇ 3 ⁇ is an absorption coefficient at the position of the distance d
  • O(d) is a light intensity at the position of the distance d.
  • the Gruneisen coefficient ⁇ which is an elasticity value, is obtained by dividing a product of a thermal expansion coefficient beta and the square of the sound speed c, by a specific heat at constant pressure Cp.
  • the Gruneisen coefficient ⁇ is a substantially constant value.
  • ⁇ 0 is a light quantity of pulsed light that is emitted on the surface of the analyte. Light is exponentially attenuated in the analyte by
  • the local light intensity O(d) can be expressed as follows:
  • Patent Literature [0005] PTL 1 US Patent No. 5840023
  • the major factor of the irradiation unevenness is that when a reflection mirror or the like is used as a light guide unit, very small irregularities of a reflection surface of the mirror may unevenly reflect the laser light, resulting in appearance of speckles. In contrast, if the reflection mirror is not used but an optical fiber is used as a light guide unit for the laser light, the speckles do not appear at the reflection surface. However, if a light path is determined with the optical fiber, an incident angle and an exit angle of the light to and from the optical fiber have to be precisely controlled to finally obtain a uniform irradiation distribution. If a light axis of incident light to the optical fiber is deviated from a light axis that is expected when the optical fiber is designed, when the light is exited from the optical fiber, irradiation unevenness may occur .
  • the value ⁇ 0 may vary depending on the position on the surface of the analyte.
  • the irradiation intensity unevenness within the light irradiation region on the surface of the analyte affects a photoacoustic wave signal intensity, the signal which is generated by the irradiation light.
  • the present invention is made in light of the situations.
  • the present invention provides a photoacoustic apparatus capable of recognizing light quantity unevenness, which occurs on a surface of an analyte, and decreasing image unevenness resulted from the light quantity unevenness.
  • the present invention also provides a photoacoustic apparatus capable of detecting an abnormal event with a simple configuration if the abnormal event occurs in a light source or an optical system.
  • a photoacoustic apparatus includes a light source configured to irradiate an analyte with light; an optical system configured to guide the light from the light source to the analyte; a detecting unit including a receiving element configured to receive an acoustic wave that is generated in the analyte by the light; a signal processing unit configured to acquire information about the inside of the analyte from a detected signal that is acquired from the detecting unit; an optical absorber configured to absorb the light from the light source; and a calculation unit
  • the photoacoustic apparatus includes the optical absorber and the detecting unit receives the photoacoustic wave generated from the optical absorber. Accordingly, the light quantity unevenness occurring at the surface of the analyte can be recognized, and the image unevenness resulted from the light quantity unevenness can be reduced.
  • the photoacoustic apparatus includes the optical absorber, and the intensity of the photoacoustic wave generated from the optical absorber corresponds to the state of light irradiation. Accordingly, if a failure occurs in the light source or the optical system, the failure can be recognized with the simple configuration.
  • FIG. 1 is a block diagram schematically showing a configuration of a photoacoustic apparatus according to a first embodiment of the present invention.
  • Fig. 2 illustrates an arrangement state of an optical absorber according to the first embodiment of the present invention.
  • FIG. 3 schematically illustrates a calculation principle for an irradiation intensity distribution
  • Fig. 4 is a block diagram showing an inner configuration of a signal processing unit according to the first embodiment of the present invention.
  • Fig. 5 is a flowchart showing a process for calculating an irradiation profile according to the first embodiment of the present invention.
  • Fig. 8 is a block diagram schematically showing a configuration of a photoacoustic apparatus according to a second embodiment of the present invention.
  • the photoacoustic apparatus is a photoacoustic imaging apparatus that acquires information about the inside of an analyte (in particular, forms an image of the information) . If the analyte is a living body, the photoacoustic apparatus can form an image of living body information for the purpose of diagnosis of a malignant tumor or a vascular disease, or follow-up of a chemical treatment.
  • the "living body information" is an acoustic-wave source distribution generated through light irradiation.
  • the "living body information" is an initial- sound-pressure distribution in the living body; a light- energy absorption-density distribution obtained by the former distribution; or a substance density distribution of substances that form a living tissue obtained by the former two distributions.
  • the substance density is an initial- sound-pressure distribution in the living body; a light- energy absorption-density distribution obtained by the former distribution; or a substance density distribution of substances that form a living tissue obtained by the former two distributions.
  • the substance density is an initial- sound-pressure distribution in the living body; a light- energy absorption-density distribution obtained by the former distribution; or a substance density distribution of substances that form a living tissue obtained by the former two distributions.
  • distribution may be oxygen saturation.
  • the photoacoustic apparatus includes a laser light source 100, an optical system 101, and a probe 104, as a basic hardware configuration.
  • the laser light source 100 is a light source that irradiates the analyte with pulsed light.
  • the analyte (not shown) , such as a living body, is fixed between plates 103a and 103b.
  • the plates 103a and 103b face each other, and press and fix the analyte from both sides.
  • the plates 103a and 103b are occasionally called pressure plates 103.
  • the pulsed light from the light source is guided to a surface of the plate 103a by the optical system 101, that is, for example, a lens, a mirror, and/or an optical fiber. Hence, the pulsed light becomes diffused pulsed light and is emitted on the analyte.
  • an acoustic wave (typically, ultrasonic wave) is generated form the optical absorber due to thermal expansion.
  • the acoustic wave is occasionally called "photoacoustic wave.” That is, since the optical absorber absorbs the pulsed light, the optical absorber increases in temperature. The increase in temperature results in volumetric expansion of the optical absorber. Hence, an acoustic wave is generated.
  • the pulsed light desirably has a certain time width that satisfies a confinement condition of heat and stress, to efficiently confine absorption energy in the optical absorber.
  • the time width is typically in a range from about 1 to 200 nanoseconds .
  • the probe 104 that detects an acoustic wave corresponds to a detecting unit including a plurality of receiving elements that detect an acoustic wave.
  • the detecting unit detects an acoustic wave generated in the analyte, and converts the acoustic wave into an electric signal (analog signal) .
  • the detected signal acquired by the detecting unit is also called "photoacoustic signal.”
  • a signal processing unit 108 acquires information about the inside of the analyte from the photoacoustic signal.
  • a signal processing unit 108 acquires information about the inside of the analyte from the photoacoustic signal.
  • An image amplifier amplifies the photoacoustic signal acquired by the probe 104, and an A/D converter converts the signal into a photoacoustic signal as a digital signal.
  • reconfiguration unit executes arithmetical processing for the digital signal to obtain three-dimensional information. Then, an image display unit 109 displays a photoacoustic image of the analyte. All elements are controlled by a system control unit 110.
  • the single light source is provided.
  • a plurality of light sources may be used. If the plurality of light sources are used, to increase the light irradiation intensity for the living body, a plurality of light sources that oscillate light with the same
  • wavelength may be used, or to measure a difference in
  • the light source may use a pigment that allows the wavelength of oscillated light to be changed, or the light source may be optical parametric oscillators (OPO) . Accordingly, the difference in optical characteristic distribution depending on wavelengths can be measured.
  • the use wavelength may be in a range from 700 to 1100 nm. Such wavelengths are absorbed by the living body only by a little amount.
  • a wavelength range from 400 to 1600 nm, the range which is wider than the above wavelength range may be used.
  • the light emitted from the light source may propagate through an optical waveguide.
  • the optical waveguide may be an optical fiber. If the optical fiber is used, a plurality of optical fibers may be used for each of the light sources to guide the light to the surface of the living body. Alternatively, the light of the plurality of light sources may be guided to a single optical fiber, and the light may be guided to the living body through the single optical fiber. Still alternatively, a mirror that generally reflects light or an optical part, such as a lens that collects light, enlarges light, or changes the shape of light, may be used to guide the light.
  • the optical part may be any part as long as a light
  • irradiation unevenness in which the intensity of the laser light may be unevenly distributed, may occur in the optical waveguide.
  • the major factor of the irradiation unevenness is, for example, speckles appearing at the surface of a reflection mirror as described above. If a plurality of mirrors are used to determine the optical waveguide, speckles may be compositely formed every time when the light is reflected by each mirror. The irradiation profile that is finally obtained may be predicted from
  • optical fiber are precisely controlled.
  • the probe 104 of this embodiment may include a plurality of receiving elements that are two-dimensionally arranged. Since the two-dimensionally arranged elements are used, the acoustic wave can be detected simultaneously at a plurality of positions. The detection time can be reduced, and the influence of vibration of the analyte can be reduced. Also, an agent for acoustic impedance matching, such as gel or water, may be used between the probe 104 and the analyte to suppress reflection of the sonic wave.
  • an agent for acoustic impedance matching such as gel or water
  • the plates each desirably have a light transparency that does not reduce the photoacoustic effect provided by the diffused pulsed laser SPL, and an ultrasonic
  • the plates 103a and 103b may be made of acryl or polymethyl pentene.
  • the plates 103a and 103b may have any thickness as long as the thickness provides an intensity that can suppress deformation of the plates 103a and 103b during holding.
  • the plates 103a and 103b each have a thickness of about 10 mm.
  • the photoacoustic apparatus includes an optical absorber 102 that particularly absorbs light that is emitted from the light source, as a feature of the photoacoustic apparatus.
  • the optical absorber 102 may be formed of a solid color substance such as graphite. If a specific analyte is present as a measurement subject, the optical absorber 102 may be made of a material that exhibits a photoacoustic characteristic obviously different from the photoacoustic characteristic of the analyte. To be more specific, if the analyte is a human body, for example, a black gel ball may be used.
  • the optical absorber 102 may be desirably arranged in the plate 103a or 103b or on the surface of that plate.
  • Fig. 2 illustrates an arrangement relationship between the optical absorber and a measurement region (actual measurement region 500) in which the analyte is arranged, when the plate 103b is viewed from the probe 104.
  • the optical absorber 102 with a certain size is arranged in a region other than the measurement region.
  • the size of the optical absorber 102 affects the frequencies of the photoacoustic wave generated from the optical absorber 102, and hence, is determined on the basis of a frequency band to be measured.
  • a fundamental frequency of a photoacoustic wave from the analyte functions as a reference.
  • the photoacoustic wave has a feature that a signal with a large N-type waveform appears.
  • a peak frequency Fc of the N-type waveform can be expressed as follows:
  • D is a diameter if the optical absorber is spherical
  • a tissue (malignant tumor) to be measured has a size in a range from about 1 to 20 mm.
  • the optical absorber 102 has a size similar to the size of the tissue.
  • the optical absorber 102 may be desirably spherical, because the intensity, frequency, and propagation of the photoacoustic wave generated from the optical absorber 102 can be predicted through analysis.
  • the laser light source 100 that irradiates the optical absorber 102 with the light is also used as the laser light source 100 for normal diagnostic measurement in this embodiment. Alternatively, different laser light sources may be used for those purposes.
  • the optical absorber 102 may include a plurality of optical absorbers 102. This is because the irradiation intensity distribution can be calculated by an easy method, which will be described later. If the
  • the optical absorbers 102 desirably have the same size and are desirably made of the same material .
  • the pressure plate 103 is present between the analyte and the probe 104.
  • a time required for the photoacoustic wave to transmit through the pressure plate 103 in the thickness direction may be a wasted time. That is, data from the time at which the laser light is emitted to the time at which the photoacoustic wave passes through the pressure plate 103 cannot be used for the reconfiguration of the diagnostic image. In other words, if the actual diagnostic measurement is carried out, the data for a predetermined period (or the time required for the photoacoustic wave to transmit through the pressure plate 103) from the time at which the laser light is emitted need not be acquired.
  • optical absorbers 102a, 102b, and 102c are arranged in the plate 103a.
  • the probe 104 including the plurality of
  • receiving elements detects acoustic waves generated from the optical absorbers 102a, 102b, and 102c. It is assumed that the receiving elements respectively located directly below the optical absorbers 102a, 102b, and 102c are receiving elements 104a, 104b, and 104c.
  • a ratio of intensities of the pulsed light that is emitted on the optical absorbers 102a, 102b, and 102c is, for example, 95:100:85.
  • optical absorbers 102a, 102b, and 102c are made of the same material and have the same size, sound pressures of acoustic waves generated from the optical absorbers 102a, 102b, and 102c have the above ratio.
  • the acoustic waves generated from the optical absorbers 102a, 102b, and 102c respectively arrive at the receiving elements 104a, 104b, and 104c, which are respectively arranged directly below the optical
  • the radio of signal intensities of the receiving elements is 95:100:85 as described above. Owing to this, if the signal processing unit 108 calculates maximum amplitudes of the received signals from the receiving elements 104a, 104b, and 104c, the light intensities of the light emitted on the optical absorbers 102a, 102b, and 102c can be obtained. Accordingly, the irradiation intensity distribution can be calculated for the three points in the light irradiation region of the plate 103a. For example, the receiving element 104b detects the acoustic wave from the optical absorber 102b and then detects the acoustic wave from the other optical absorber. In this situation, the signal intensity at early timing is used.
  • the plurality of optical absorbers do not have to be provided.
  • a single optical absorber may be provided.
  • the optical absorber may be moved to a position at which an irradiation intensity is obtained, and the signal intensity of a receiving element that is arranged directly below the optical absorber may be compared with the other signal intensity.
  • the movement and light irradiation have to be carried out the N times. The movement is made by changing the position of the optical absorber relative to the position of the light irradiation region.
  • the light source may be moved, or the optical absorber may be moved, for example, by moving the plate 103a.
  • the plurality of optical absorbers are desirably provided. As long as the plurality of optical absorbers are arranged to be aligned with data acquisition positions for the measurement of the irradiation profile, all elements of the probe 104 can simultaneously measure the photoacoustic waves from the plurality of optical absorbers 102. For example, if an irradiation range for profile measurement corresponds to an element range of the probe 104, the measurement can be completed only by onetime measurement.
  • the optical absorbers 102 are respectively arranged above the center points of the elements of the probe 104, at positions sufficiently close to the surface of the probe, the photoacoustic wave from the optical absorber arranged above the adjacent element is incident on the target element at a large angle.
  • the element of the probe has a directivity for reception, and has a highest
  • the array transducer including the plurality of receiving elements serves as the probe 104; however, the present invention is not limited thereto.
  • a single-element probe may be alternatively used.
  • the probe 104 is desirably arranged directly below a single optical absorber and the photoacoustic measurement is desirably performed the number N times.
  • Fig. 4 illustrates the signal processing unit 108 that performs signal processing for calculating the irradiation profile in the light irradiation region, from the detected signals as described above.
  • Fig. 5 is a flowchart showing an example of calculation for the
  • the signal processing unit 108 The signal processing unit 108
  • the light source 100 and the probe 104 are moved to the position at which the optical absorber 102 is arranged (SI). Then, the light source 100 emits laser light, and the probe 104 receives a photoacoustic wave that is generated from the optical absorber 102 as the result of the laser light emission (S2). The photoacoustic wave received by the probe 104 is transmitted to the signal processing unit 108 as an analog photoacoustic signal that is detected by each receiving element.
  • a signal amplifier 301 amplifies the input analog photoacoustic signal, and an A/D converter 302 converts the analog signal into a digital signal (S3) . If the plurality of receiving elements are provided, the signal amplifier 301 and the A/D converter 302 are provided for each element.
  • a sensitivity correction unit 303 performs sensitivity correction for the photoacoustic signal that is converted into the digital signal (S4). This processing is performed if variation in sensitivity is present among the elements. In this embodiment, information about the
  • the sensitivity correction unit 303 corrects digital data from each element, on the basis of the information about the variation in sensitivity among the elements, the information which is stored in the memory 112.
  • an irradiation profile calculation unit 111 obtains an irradiation profile from the detected signal by the probe (S5) .
  • the irradiation profile is stored in the memory 112 (S6) .
  • the present invention is not limited thereto.
  • the plurality of optical absorbers 102 are arranged in a known arrangement, an intensity (correct data) of a photoacoustic wave to be received by each element of the probe 104 under an
  • distribution of light absorption coefficients acquired herein is information that is expressed by coordinates of the intensity of the acoustic wave generated from the optical absorber 102 and the source of the sonic wave, in the form of three-dimensional coordinates.
  • the distribution of the light absorption coefficients is divided by the correct data and multiplied by the expected irradiation intensity. Accordingly, the intensity distribution of the irradiation light at the position of the optical absorber 102, i.e., the irradiation profile can be calculated.
  • an irradiation adjustment unit is desirably provided.
  • the irradiation adjustment unit adjusts the light source or the optical system such that the distribution of the irradiation intensities is reduced on the basis of the calculated irradiation profile (the calculation result of the irradiation profile calculation unit 111) . Accordingly, the pulsed light with a uniform intensity can be emitted on the surface of the analyte, and the correct information about the inside of the analyte can be acquired by the PAT measurement.
  • an adjustment value calculation unit 113 (Fig. 1) is provided.
  • calculation unit 113 calculates an adjustment value for adjustment to obtain uniform light diffusion by using the light diffusing unit on the basis of the calculated
  • calculation unit 113 calculates the adjustment value, and the irradiation adjustment unit (in Method 1, the optical system 101 also serves as the irradiation adjustment unit) adjusts the degree of diffusion of the laser light.
  • the irradiation adjustment unit is an optical device that can correct the intensity distribution of incident light, such as a device called deformable mirror.
  • a device called deformable mirror may be an assembly including two piezoelectric elements bonded to each other, and the shape of the mirror can be controlled by changing a voltage in accordance with the position to which the voltage is applied.
  • a control matrix for driving the deformable mirror is prepared to correct the irradiation profile.
  • a voltage is impressed successively to the elements of the deformable mirror, and the resulted change in mirror surface is successively recorded by a wavefront sensor. Accordingly, a response matrix of the irradiation profile for the drive voltage of the elements is generated.
  • the control matrix for controlling the deformable mirror for an error of the irradiation profile is obtained.
  • the above adjustment value is an impressed voltage impressed to each element for deforming the mirror surface of the deformable mirror.
  • irradiation profile error signal at the position of each element is obtained from the irradiation profile, and the vector is multiplied by the response matrix of the irradiation profile. Accordingly, an adjustment value to be fed back to the deformable mirror is obtained.
  • the calculated irradiation profile is fed back to a deformation profile of the
  • the deformable mirror the position which is aligned with the position of the optical absorber 102, is expected as a corresponding irradiation profile value.
  • the irradiation profile error signal is compared with a certain upper limit that is determined in advance (S13) . If the error exceeds the upper value, irradiation correction is performed by the following method.
  • irradiation profile error signal is applied to the control matrix for driving the deformable mirror, and an input signal for driving the deformable mirror is acquired (S14).
  • the deformation control for the mirror surface is performed, and correction for bringing the irradiation profile closer to the uniform irradiation profile is performed (S15) .
  • the analyte is arranged between the plates 103a and 103b and pressed and held by the plates 103a and 103b for the photoacoustic measurement. It is assumed that the analyte has a uniform surface profile because the analyte is pressed.
  • the laser light source 100 and the probe 104 are driven and moved to the measurement position (S20) .
  • the laser light emitted from the laser light source 100 is guided by the waveguide of the optical system 101, and propagates through the analyte. Part of the light energy propagating through the analyte is absorbed by an optical absorber, such as a blood vessel, and becomes a
  • the probe 104 receives the
  • the image reconfiguration unit 304 in the signal processing unit 108 analyzes the digital data, and provides voxel data for the inside of the analyte (S24).
  • the voxel data is data obtained by dividing the inside of the analyte into small blocks
  • the light of the point sources is rapidly attenuated and diffused on the surface of the analyte. Assuming that the light
  • a distribution at this time is an illuminance distribution, by hypothesizing an optical coefficient of the analyte, a two- dimensional light distribution, that is, the illuminance distribution on the surface of the analyte can be obtained (S25) .
  • a three-dimensional light quantity distribution that is, a light quantity distribution of the light propagating through the analyte is calculated by using light diffusion equation, transport equation, or Monte Carlo light propagation simulation (S26) .
  • a photoacoustic intensity distribution of the inside of the analyte with regard to the irradiation profile can be obtained by using Expression (1) for respective corresponding positions (S27).
  • the image display unit 109 displays the distribution by a two-dimensional graphic or a three- dimensional graphic (S28). As described above, by
  • the image unevenness due to the irradiation unevenness can be reduced.
  • acoustic waves from the actual measurement range that is larger than the aperture size of the probe 104 and from the optical absorber 102 arranged at a certain position are desirably measured.
  • the probe 104 includes a drive unit so that the probe 104 is moved to a desirable measurement position to face an
  • a probe drive unit 105 serves as the drive unit for the probe, and a light source drive unit 106 for driving the laser light source and the light diffusing unit (in Method 2, the optical system 101 also function as the light diffusing unit) serves as the drive unit.
  • the drive unit for the light source does not have to move the laser light source 100 and the light diffusing unit.
  • the drive unit may only move an optical system part, such as a mirror for reflecting laser light or a tool for adjusting a light path, arranged so that the analyte or the optical absorber 102 is finally irradiated with the diffused light.
  • a feature of a second embodiment is that a judging unit is provided.
  • the judging unit judges whether the intensity of the detected signal when the receiving element receives the acoustic wave generated from the optical absorber is within a predetermined intensity range
  • FIG. 8 is a block diagram showing a photoacoustic apparatus according to the second embodiment of the present invention.
  • a serial console 400 is a threshold setting unit configured to set an upper limit and a lower limit for the reception intensity of the photoacoustic wave PA.
  • the threshold setting unit is configured such that a user can set the upper limit and the lower limit for the reception intensity by a typical user interface, such as a control panel or a serial console, connected with the apparatus .
  • An abnormal-light-quantity detecting unit 401 which serves as the judging unit, detects an abnormal light quantity by recognizing the reception intensity of the photoacoustic wave PA as the intensity of the diffused pulsed laser light SPL. The upper and lower limits of the reception intensity designated by the user are stored in the memory 112. When the photoacoustic wave is received from the optical absorber 102, the abnormal-light-quantity detecting unit 401 references the set threshold and makes the judgment for the abnormal light quantity.
  • the abnormal-light- quantity detecting unit 401 detects the abnormal state.
  • the operation is brought into an error state, and the
  • the system of this embodiment limits the laser light emission control, stops the
  • the measurement work cannot be performed until the problem is addressed by, for example, part replacement.
  • Fig. 9 briefly illustrates detection for
  • the system is based on the premise of that the variation in sensitivity among the elements of the probe 104 is ignorable or
  • This embodiment provides a method of
  • photoacoustic waves PA from the optical absorber 102 and from only one of the plurality of elements of the probe 104 are measured to detect the irradiation unevenness with the diffused pulsed laser light.
  • Fig. 9 briefly illustrates the measurement for the irradiation unevenness in a plane parallel to the flat
  • the attention element 501 starts measurement from a measurement start point 502, and successively performs the measurement while being moved by the probe drive unit 105 along a measurement locus 503, for the measurement of distribution unevenness of the diffused light of the entire measurement region 504 for the diffused light irradiation profile.
  • the control has to be
  • the attention element 501 the position for the measurement of the light intensity within the measurement range 504, and the optical absorber 102 are aligned in an irradiation direction. Since the optical absorber 102 is fixed by the pressure plate 103, the probe drive unit 105 and the light source drive unit 106 are controlled to attain the above-mentioned relative positional relationship of the three elements. By repeating the movement on the measurement locus 503 and the photoacoustic measurement, the photoacoustic waves in the measurement range 504 are acquired.
  • Photoacoustic wave signals acquired in this way are processed in a manner similar to the process for calculating the irradiation profile. Hence, the irradiation profile for the measurement range 504 is calculated.
  • the photoacoustic apparatus includes a plate having a plurality of optical absorbers 102, and a movable mechanism that moves the plate so that the optical absorbers 102 are irradiated with pulsed laser light only during measurement for irradiation
  • the mount area for such optical absorbers 102 has to be
  • the optical absorbers 102 are provided at the pressure plate 103 in the measurement region. In this case, the photoacoustic waves from the optical absorbers 102 are generated even during the normal
  • photoacoustic wave less affects the measurement. However, if the number of optical absorbers 102 increases, the acoustic waves are generated by a large amount, and the effect of the acoustic waves become no longer ignorable.
  • a characteristic measurement plate (not shown) including the plurality of optical absorbers 102 is provided in addition to the plate 103a that fixes the analyte. Further, a movable mechanism
  • the measurement plate is moved away from the measurement region to a position at which the characteristic measurement plate is not irradiated with the laser light to prevent the unused acoustic wave from being generated.
  • the present invention may be implemented by executing the following processing.
  • the processing includes that a system or an apparatus is
  • program software that provides the functions of any of the embodiments through a network or a recording medium of any kind, and a computer (or CPU, MPU, etc.) of the system or the apparatus reads and executes the program.
  • the photoacoustic measurement apparatus capable of precisely performing the photoacoustxc wave measurement by reducing the effect by the irradiation unevenness of the laser light to the
  • photoacoustic wave signal intensity can be provided. Also, to detect the irradiation unevenness of the laser light, with the present invention, the detection is enabled by using the ultrasonic probe for the photoacoustic wave measurement. That is, the irradiation unevenness can be detected with a low cost because a detection sensor does not have to be newly added.
  • the abnormal state of the diffused light intensity can be indirectly detected and hence, a failure of the optical system part, such as the light diffusing unit, can be detected.
  • the photoacoustic wave measurement by detecting the abnormal intensity of the photoacoustic wave intensity, the abnormal state of the diffused light intensity can be indirectly detected and hence, a failure of the optical system part, such as the light diffusing unit, can be detected.

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  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

La présente invention concerne un appareil photoacoustique capable de reconnaître les inégalités de quantité de lumière qui se produisent à la surface d'un analyte, et de diminuer les inégalités d'image dues aux inégalités de quantité de lumière. L'appareil photoacoustique comprend : une source lumineuse, configurée pour irradier un analyte avec de la lumière ; un système optique, configuré pour guider la lumière entre la source lumineuse et l'analyte ; une unité de détection, comprenant un élément récepteur configuré pour recevoir une onde acoustique générée dans l'analyte par la lumière ; une unité de traitement de signaux, configurée pour acquérir des informations concernant l'intérieur de l'analyte à partir d'un signal détecté acquis par l'unité de détection ; un absorbant optique, configuré pour absorber la lumière provenant de la source lumineuse ; et une unité de calcul, configurée pour calculer une répartition de l'intensité d'irradiation de la lumière en se basant sur un signal détecté acquis lorsque l'élément récepteur reçoit l'onde acoustique générée depuis l'absorbant optique.
PCT/JP2010/071748 2009-12-11 2010-11-26 Appareil photoacoustique, et procédé de commande associé WO2011070985A1 (fr)

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JP2009282287A JP5538855B2 (ja) 2009-12-11 2009-12-11 光音響装置及び該装置の制御方法
JP2009-282287 2009-12-11

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EP2382917B1 (fr) 2010-04-27 2018-11-07 Canon Kabushiki Kaisha Appareil d'obtention de données d'affichage et procédé d'obtention de données d'affichage
EP3427645A1 (fr) * 2010-04-27 2019-01-16 Canon Kabushiki Kaisha Appareil d'obtention de données d'affichage et procédé d'obtention de données d'affichage
EP2382917B2 (fr) † 2010-04-27 2022-03-23 Canon Kabushiki Kaisha Appareil d'obtention de données d'affichage et procédé d'obtention de données d'affichage
US11213209B2 (en) 2011-11-22 2022-01-04 Fujifilm Corporation Device and method for processing photoacoustic signal
EP2844149A4 (fr) * 2012-05-03 2016-01-20 Samsung Electronics Co Ltd Appareil à onde ultrasonore induite par laser et procédé associé
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JP2014113466A (ja) * 2012-11-15 2014-06-26 Canon Inc 被検体情報取得装置
US20140371589A1 (en) * 2013-06-13 2014-12-18 Canon Kabushiki Kaisha Subject information obtaining apparatus
EP3351166A1 (fr) * 2017-01-23 2018-07-25 Canon Kabushiki Kaisha Appareil photo-acoustique

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WO2011070985A4 (fr) 2011-08-18
US9084560B2 (en) 2015-07-21
US20130031982A1 (en) 2013-02-07
JP5538855B2 (ja) 2014-07-02
JP2011120795A (ja) 2011-06-23

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